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Climate Dynamics

, Volume 36, Issue 5–6, pp 1083–1105 | Cite as

Regional climate modelling of the 2006 West African monsoon: sensitivity to convection and planetary boundary layer parameterisation using WRF

  • Emmanouil FlaounasEmail author
  • Sophie Bastin
  • Serge Janicot
Article

Abstract

Regional climate model (RCM) is a valuable scientific tool to address the mechanisms of regional atmospheric systems such as the West African monsoon (WAM). This study aims to improve our understanding of the impact of some physical schemes of RCM on the WAM representation. The weather research and forecasting model has been used by performing six simulations of the 2006 summer WAM season. These simulations use all combinations of three convective parameterization schemes (CPSs) and two planetary boundary layer schemes (PBLSs). By comparing the simulations to a large set of observations and analysis products, we have evaluated the ability of these RCM parameterizations to reproduce different aspects of the regional atmospheric circulation of the WAM. This study focuses in particular on the WAM onset and the rainfall variability simulated over this domain. According to the different parameterizations tested, the PBLSs seem to have the strongest effect on temperature, humidity vertical distribution and rainfall amount. On the other hand, dynamics and precipitation variability are strongly influenced by CPSs. In particular, the Mellor–Yamada–Janjic PBLS attributes more realistic values of humidity and temperature. Combined with the Kain–Fritsch CPS, the WAM onset is well represented. The different schemes combination tested also reveal the role of different regional climate features on WAM dynamics, namely the low level circulation, the land–atmosphere interactions and the meridional temperature gradient between the Guinean coast and the Sahel.

Keywords

Regional modelling AMMA field experiment in 2006 Physics parameterization schemes West African monsoon onset 

Notes

Acknowledgments

The authors are grateful for the help of Philippe Weill to install the model on the IPSL servers. We are also thankful to the Climate Diagnostics Center (NOAA, Boulder, CO) and to the NCEP for the OLR and Final Analyses (FNL) data. Finally, we would like to thank the anonymous reviewers for their fruitful comments. Based on French initiative, AMMA was built by an international scientific group and is currently funded by a large number of agencies, especially from France, UK, US and Africa. It has been the beneficiary of a major financial contribution from the European Community’s Sixth Framework Research Programme. Detailed information on scientific coordination and funding is available on the AMMA International website http://www.amma-international.org.

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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Emmanouil Flaounas
    • 1
    Email author
  • Sophie Bastin
    • 1
  • Serge Janicot
    • 2
  1. 1.UPMC, CNRS/INSU, LATMOS/IPSLParis cedex 05France
  2. 2.UPMC, IRD, LOCEAN-IPSLParisFrance

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